Pharm 236 Ch 49

Front 1

___________ sometimes called arrhythmias are abnormalties in heart rate or rhythm.

Back 1

Dysrhythmias

Front 2

The mechanical or pump activity of the heart resides in _________ tissue.

Back 2

Contractile

Front 3

___________ is the hearts ability to generate an electrical impulse.

Back 3

Automaticity

Front 4

Initiation of an electrical impulse depends predominately on the movement of sodium and _____________ ions into a myocardial cell and movement of potassium ions out of the cell.

Back 4

Calcium

Front 5

The ability of a cardiac muscle cell to respond to an electrical stimulus is called ___________

Back 5

excitability

Front 6

Describe how the electrophysiology of the heart causes it to beat.

Back 6

The heart is an electrical pump. Its electrical activity resides primarily in the psecialized tissues that can generate and conduct an electrical impulse. Although impulse are also conducted through muscle cells, the rate is much slower. The mechanical or pump activity resides in contractile tissue. Normally, these actvities result in effective cardiac contraction and distribution of blood throughout the body. Heart beats occur at regular intervals and consist of four events; Stimulation from an electrical impulse, transmission of the electrical impulse to adjacent conductive or contractile tissue, contraction of atria and then ventricles, and relaxation of the atria and then ventricles.

Front 7

What is automaticity and how does it affect the heart beat?

Back 7

Automaticity is the hearts ability to generate an electrical impulse. Any part of the conduction system can spontaneously start an impulse but the SA node normally has the fastest rate of automaticity and terefor the fastest rate of spontaneous impulse formation. Because it has a faster rate of electrical discharge or depolarization than other parts of the conduction system the SA node serves as the pacemaker site.

Front 8

What is excitability and how does it affect the heart beat?

Back 8

The cardiac muscle cell to respond to an electrical stimulus is called exitability. The stimulus must reach a certain threshold to cause contraction. After contraction sodium and calcium ions return to the extracellular space, muscle relaxation occurs, and the cell prepares for the next electrical stimulus followed by contraction.

Front 9

Define absolute refractory period as it relates to the electrophysiology of the heart.

Back 9

After a contraction there is also a period of decreased excitability (called the absolute refractory period) during which cell cannot respond to a new stimulus. Before the resting membrane potential is reached a stimulus greater than normal can evoke a response in the cells. This period is called the relative refractory period.

Front 10

Define conductivity as it relates to the electrophysiology of the heart.

Back 10

Conductivity is the ability of cardiac tissue to transmit electrical impulses. The orderly, rhythmidc transmission of impulses to all cells is needed for effective myocardial contraction.

Front 11

Similar to quinidine in pharmacologic actions and may be given orally to adults with ventricular tachydysrhythmias.

Back 11

Disopyramide

Front 12

Indicated for the maintenance of NSR in symptomatic patients who are A fib for more than 1 weeks duration.

Back 12

Dofetilide

Front 13

The only calcium channel blockers approved for management of dysrhythmias.

Back 13

Diltiazem and verapamil

Front 14

Related to the local anesthetic procaine and is similar to quinidine in actions and uses

Back 14

Procainamide

Front 15

An antidysrhythmic for treating serious ventricular dysrhthmias associated with acute myocardial infraction, cardiac catheterizaiton, cardiac surgery, and digitalis induced ventricular dysrhythmias.

Back 15

Lidocaine

Front 16

Mr. Bennet present to the ER with palpitations, dizziness, shortness of breath, and crushing chest pain. THe physician orders the administration of lidocaine via an intravenous route.

What is the mechanism of action of lidocaine? If Mr. Bennet were to develop an atrial dysrhythmia what would you expect the physician to do with his lidocaine prescription?

Back 16

Lidocaine decreases myocardial irritability (automaticity in the ventricles. Lidocaine has little effect on atrial tissues and therefor is not useful in treating atrial dysrhythmias.

Front 17

Mr. Bennet present to the ER with palpitations, dizziness, shortness of breath, and crushing chest pain. THe physician orders the administration of lidocaine via an intravenous route.

Initially the physician orders a bolus dose of lidocaine to treat Mr. Bennet. What effect does a bolus dose have?

Back 17

A bolus dose has a rapid onset and a short duration of action. After IV administration of a bolus dose of lidocaine therapeutic effects occur within 1 to 2 mins. and last approximately 10 to 20 mins. This characteristic is advantageous in emergency management bu limits lidocaine use to intensive care settings.

Front 18

Mr. Bennet present to the ER with palpitations, dizziness, shortness of breath, and crushing chest pain. THe physician orders the administration of lidocaine via an intravenous route.

Mr. Bennet's wife arrives and informs you that her husband is an alcoholic and is diagnoses with cirrhosis of the liver. How would treatment of this patient change based on this new information? If the patients history revealed that he broke out in hives after receiving procaine how would this information change the treatment approach?

Back 18

The physician would decrease the dosage of the lidocaine in an alcoholic patient or in a patient with liver damage. Lidocaine is metabolized in the liver so the dosage must be reduce in patient with hepatic insufficiency or right sided heart failure to avoid drug accumulation and toxicity. Hives as well as SOB are signs of an allergic reaction. Lidocaine is contraindicated for such a patient.

Front 19

Mr. Bennet present to the ER with palpitations, dizziness, shortness of breath, and crushing chest pain. THe physician orders the administration of lidocaine via an intravenous route.

The physician orders measurement of Mr. Bennet's lidocaine serum levels and the laboratory indicates that the level is 0.75mcg/mL. What does this result tell you?

Back 19

With a lidocaine serum level of 0.75mcg/mL, the patient has achieved a sub-therapeutic level if the drug. Therapeutic serum levels of lidocaine are 1.5 to 6mcg/mL. Toxic serum levels are those greater than 6mcg/mL.

Front 20

What is a life threatening risk associated with the use of amiodarone?

Back 20

Pulmonary toxicity

Rationale: The FDA has issued a black box warning for amiodarone recommending that it be used only in patients with life threatening dysrhythmias due to the risk of developing potentially fatal pulmonary toxicity.

Front 21

Amiodarone is a potassium channel blocker that prolongs conduction in all cardiac tissues. Which of the following is another effect of amiodarone? (select all that apply)

a. It decreases heart rate

b. It deminishes bradydysrhythmias

c. It increases contractility of the left ventricle.

d. It decreases contractility of the left ventricle.

Back 21

a,d

Rationale: Amiodarone is a potassium channel blocker that prolongs conduction in all cardiac tissues and decreases heart rate; it also decreases contractility of the left ventricular.

Front 22

The FDA has issued a black box warning for disopyramide because of its known ________ properties.

Back 22

Prodysrhythmic

Front 23

Which two class IV drugs are the only calcium channel blockers approved for the management of dysrhythmias?

Back 23

1. Dilitiazem
2. Verapamil

Front 24

Mr. King is released from the hospital after a myocardial infarction. The physician prescribes a class II beta-adrenergic blocker drug. Why does the physician choose this drug?

Back 24

It is effective in reducing mortality after myocardial infarction.

Rationale: Class II beta adrenergic blockers are being used more extensively because of their effectiveness in reducing mortality after MI and in patients with HF.

Front 25

Flecainide, propafenone, and moricizine are unique in that they have no effect on the re-polarization phase but do have the following effect:

Back 25

They decrease conduction in the ventricles.

Rationale: Flecainide, propafenone, and moricizine are class 1C drugs that have no effect on the re-polarization phase but greatly decrease conduction in the ventricles.

Front 26

Lidocaine is the prototype of class IB antidyrhythmics used for treating serious ventricular dysrhythmias associated with which of the following conditions? (select all that apply)

a. cardiac catheterization

b. cardiac surgery

c. digitalis induced ventricular dysrhythmias.

d. Digitalis induced atrial dysrhythmias.

Back 26

a,b,c

Rationale: Ladocaine is the prototype of class IB antidysrhythmics used for treating serious ventricular dysrhythmias associated with acute myocardial infarction, cardiac catheterization, or cardiac surgery and digitalis induced ventricular dysrhythmias.

Front 27

Which of the following is an effect of quinidine, the prototype of class IA antidysrhythmics?

a. It reduces automaticity

b. It speeds conduction.

c. It prolongs the refractory period.

d. It slows the refractory period.

Back 27

a,c

Rationale: Quinidein the prototype of class IA antidysrhythmics, reduces antomaticity, slows conduction and prolongs the refractory period. Phenytoin may be used to treat dysrhythmias produced by digoxin intoxication.

Front 28

Initiation of an electrical impulse depends predominately on the movement of ________ and ____________ ions into a myocardial cell movement of potassium ions out of the cell.

Back 28

Sodium and calcium

Front 29

___________ is the most common dysrhythmia.

Back 29

Atrial fibrillation

Front 30

You are visiting the home of a client who is prescribed antidyrhythmic medication. Part of your teaching will include the reporting of which of the following?

a. Increased functional status

b. Improved functional status

c. Dizziness

d. Improved mentation.

Back 30

c

Rationale: Patients receiving chronic antidysrhythmic drug therapy are likely to have significant cardiovascular disease. With each visit the home care nurse needs to asses the patients physical, mental, and functional status and evaluate pulse and blood pressure. In addition, patients and caregivers should be taught to report symptoms ex. dizziness, fainting, or chest pain and to avoid OTC agents unless discussed with a healthcare provider.

Front 31

Mr. Garnet is admitted to the critical care unit after experiencing a myocardial infarction and subsequent serious dsyrhythmias. He is treated successfully for ventricular dysrhythmia, and the physician orders continuous IV therapy. Which of the following may cause further development of dysrhythmias?

a. Elevated LFT's

b. Hypotenstion

c. Electrolyte imbalances

d. Elevated blood glucose

Back 31

c.

Rationale: Because serious problems may stem form either dysrhythmias or their treatment healthcare providers should be adept in preventing recognizing and treating conditions that predispose to the development of serous dysrhythmias. Ex. electrolyte imbalances, hypoxia. If dysrhythmias cannot be prevented early recognition and treatment are needed.

Front 32

Mrs. Bertram is prescribed digoxin. Six months later she is diagnosed with impaired liver function. As her long term care nurse which of the following would your expect the physician to do?

a. Increase the dose of digoxin

b. Continue to monitor the client

c. Decrease the dosage of digoxin

d. Discontinue the digoxoin.

Back 32

c.

Rationale: Dosages of digoxin, disopyramide, propafenone, and quinidine should be reduced in patients with impairment of hepatic function.

Front 33

Mrs. Carter, age 75 presents to his physicians with a cardiac dysrhythmia. They physician chooses to treat the dysrhythmia because of which of the following types of symptoms?

a. Symptoms related to circulatory impairment.

b. Symptoms related to diabetic neuropathy.

c. Symptoms related to Meniere's disease

d. Symptoms related to cardomyopathy.

Back 33

a

Rationale: Cardiac dysrhythmias are common in older adults but in general only those causing symptoms of circulatory impairment should be treated with antidysrhythmic drugs.

Front 34

________________ is more common in children with structural heart disease or significant dysrhythmias.

Back 34

Prodysrhythmia

Front 35

_________ is a beta blocker most commonly used in children

Back 35

Propanolol

Front 36

Michael S. is treated in the pediatric unit with adenosine. He weighs less than 50kg. How would you expect the IV dose to be administered?

Back 36

Initially, a 0.1mg/kg IV push is given with a maximum dose administered of 6mg.

Rationale: Adenosine is administered like the adult dosing for children over 50kg. For children weighing less than 50kg, initially 0.1mg/kg IV push is given , with a maximum dose administration of 6mg. If this initial dose is ineffective a repeat dose of 0.2 mg/kg up to the maximum of 12mg may be administered by IV push.

Front 37

Mrs. Benz presents to the ER department with dizziness, SOB, and palpitations. This is the third episode of A fib for this client in 1 month. A low dose of which of the following drugs is the pharmacologic choice for preventing recurrent A fib after electrical or pharmacologic conversion?

a. Diltiazem

b. Nifedipine

c. Amiodarone

d. Amlodipine

Back 37

c.

Rationale: Low dose amidarone is a pharmacological choice for preventing recurrent A fib after electrical or pharmacological conversion. The low doses cause fewer adverse effects than the higher ones used for life threatening ventricular dysrhythmias.

Front 38

Nonpharmacologic management for PSVT with mild or moderate symptoms includes which of the following techniques?

a. Valsalvas maneuvers

b. Carotid sinus massage

c. Warm baths

d. Brisk exercise

Back 38

a, b

Rationale: Non pharmacologic management is preferred at least initially for several dysrhythmias. For example, sinus tachycardia usually results from such disorders as dehydration, fever, infection, or hypotention and intervention and management should attempt to relieve the underlying cause. For PSVT with mild or moderate symptoms Valsalva's maneuver, carotid sinus massage, or other measures to increase vagal tone are preferred.

Front 39

Name the Class I sodium channel blockers

Back 39

Quinidine

Procainamide (pronestyl, procanbid)
Disopyramide (Norpace)

Front 40

___________ is the prototype of Class IA sodium channel blockers and reduced automaticity and lows conduction and prolongs the refractory period. Therapeutic levels are 2 - 5 mcg/mL and are attained wiht in 1hr and persists for 6 to 8 hrs. It is highy bound to serum albumin and has a half life of about 6hrs. It is metabolized in the liver and excreted in the urine. Serum levels greater than 5 mcg per milliliter are toxic.

Back 40

Quinidine

Front 41

________ is contrainidcated in patients with severe uncompensated heart failure or with heart block becase it depresses myocardial contractility and conduction through the AV node.

Back 41

Quinidine